Process for treating hydrocarbons



June 13, 1944. w. A. SCHULZE 2,351,154

PROCESS FOR TREATING HYDROCARBONS Filed April 8, '1940 BOLVNOILDVHJHQLVNOILDVHA CATALYST CHAMBER HOLVNOILDVHJ H25 26 REMOVER HOLVNOILDVHJUOLVNOILDVHJ CONDENSER CATALYST CHAMBER HOLVNOIJDVHA CHAMBER CATALYSTFURNACE HEATER INVENTOR WALTER A. SCHULZE BY I v @mw suppressors. I

Patented June 13, 1944 UNITED STATES PATENT j orF-lcr:

g 2,s5i,1sf4. j k mooassroa Tar-Lanna menaocaanous Walter a. sebum,momma, kla., assignor to Phillips Petroleum Company, a corporation of pication April ,Srial;No.328,545

Q, f Claims. (Cl; 196-23) The present invention relates toa' process forthe production of motorffuel fromcrizdehydmat elevated temperaturesfor'the production of motor. fuel with improved antiknockcharacteristics and a high response to lead-alkyl knock Previousinvestigation has shown that the, oc-

tane number response of motor fuels to; additions-of tetraethyl lead isa variant factor and greatly affected by the sulfur content of saidmotor fuel. Improvement in the. so-called lead response of gasolinehasbeen obtained by the process of vapor-phase catalytic decomposition 1of the sulfur compounds, e. 1 g. U. S. Patent 2,016,271issuedOctoberB;l935.to Schu1zeand Buell. Suoh a process is applicable tothe treatment of motor fuel from any source, but the results varysomewhat when said process is ap-p plied to cracked gasolines. Y a a Ihave now found that greatly improved results may be obtained by aradical alteration of the processing steps used in the manufacture ofthe gasollnes from the basestocksa This discovery involves several coacting steps which maybe briefly described as follows: (1). acrude oilis heated under pressure and flashed under such conditions that thetemperature of the vapors leaving the tower is in the range of 600 to800' E,

the vaporizable constituents at said temperatures thus being separatedfrom the non-vaporizable material; (2) the aforementioned vaporscomprising hydrocarbonsg-in the range of gaso e,

,naphthas and gas ,oils are then passed over a dea the hydrocarbonsboiling above thegasoline range 'into lower boiling components.Additional, steps which may be included are the catalytic polymerizationof the light unsaturated hydrocarbons, primarily propylene andbutylenes, and of finally blending these various components of highantiknock characteristics and low su fur. content into tent of thecracking stocks,the.polymer gaso ine,

also, will be much lower in sulfur contentthan that normally produced inthe refinery charging undesulfurized stocks Such an innovation as theseries of steps outlined above is particularly advantageous because "ithas been found thatthe sulfur compoundsinvolved are less refractory inthe naphthas and gas oils prior to cracking, and hence are removed to agreater extent than they wouldbe from the cracked distillates. Also,with propercontrol of desulfurizing conditions, catalyst poisoning maybe greatly reduced" and longer operating cycles obtained by treatingthetotal vaporizable material described above. v

Several processes are known for the desulfurization-of heavy residualoils, asphalts. tars and coal pastes but such processes involve highpressure hydrogenation and are too expensive for application to thetreatment of potential motor fuel stocks My discovery, however, thatheavy naphthas and gas oil fractions may be treated'in the is (toprovide. a unitary process for producing an improved motor fuel sulfur."

An additional object of the present invention is to provide apro'cessfor economically producing a motor fuel with improved anti-knockcharacteristics and a high response to knock suppressors.

As stated previously, I have-found that the from crude oil containing-maximum reduction in the sulfur content and maximum improvement in.the-lead response of the finished motor fuel-(which in this instance isconsidered as a blend of the various streams produced from the crudeoil) may be obtained by heating the crude. petroleum oil under pressureto temperatures within the range desired for catalytic vapor-phasedesulfurization, releasing the pressure on thetheated-oil to allow allthe material vaporizable at said temperatures to separate from thenon-vaporizable material, and passing thevapors without substantialcondensation over, a contact catayst capable of effecting decompositionof the organic sulfur compounds. By operatingin this manner anystep-wise fractionation or separation of liquid components of said vaporis avoided with resultant savings in I processing costs. Further,operation ,in this manimproved motor fuels. Due to the low sulfur con-6! a s t p sible to tain good resultsin desulfurizing the heavierfractions such as gas oil, since, said fractions because of high boilingpoint and large content of asphaltic and/or waxy bodies are notadaptable to treatment'inthe absence of the light, lower-boilingcomponents.

Passage of the vapors of a crude. petroleum oil at suitable flow ratesof 1 to liquid volumes per hour'per volume of catalyst over acontactcatalyst at temperatures between 600 and 800 F. and at pressures betweenzero and 100 pounds per 7 square inch results in the decomposition of a.

substantial proportion of the organic sulfur com-- I pounds intohydrogen sulfide without any substantial decomposition of thehydrocarbon constituents. Due to the absence of unsaturatedhydrocarbons, there is no tendency for the hydrosures in the process mayrange from zero to about 300 pounds, while the fiow rate may be about0.2 to 3 liquid volumes per hour per volume of catalyst. In such anoperation the conversion temperature will depend on the percentage, oflower-boiling constituents which is left in the cracking stock afterltheseparation of straight run gasoline. Thus it is possible to operate withsubstantially all of the gasoline content of the desulfurized oil beingcharged to the cracking unit, in which casecracking temperatures may beat the higher part of the indicated range.

' This is possible because of the diluent effect of thelight gasolinewhich prevents over-conver-.

sion of the heavy ends.

- However, because of the excellent lead response and. the high blendingvalue of the low-sulfur tionatlQnrand-the latter method is preferablesince the desulfurized vapors must befractionated prior to subsequentsteps of the present invention.

7 Fractionation of the desulfurizedvapors is carried out in asuitableunit by taking the normally gaseous hydrocarbons and the straight rungas- 'oline overhead along wlththe hydrogen sulfide,

and thus separating the hydrocarbon liquids boilingwithin the range ofthe desired straight run totetraethy'l lead- This-gasoline, afterstabilizagasoline from the heavier kerosene, naphtha andas-oil-fractlons. From this overhead fraction there is obtainedastraight run gasolineof very low sulfur content and' exceedinglyhighresponse tion to remove-the normally gaseous hydrocarbolls and hydrogensulfide, is of greatvaluein blending with stocks to make leaded motorfuels H on account ofits great lead susceptibility.

The gaseous hydrocarbons from the above-de- "scribed stabilization'maybe passed to a vapor recovery plant for the'extraction of C3 and C4-hydrocarbons useful in production of motor fuels by means of thermalpolymerization and the like. The heavy naphthaand gas-oil of greatlyreduced su1fur c0ntent"is available for thermal or catalytic crackingtoproduce high octane cracked gasoline of-low sulfur'content. If thermalcracking is employed, the. resulting cracked asollne"will-have a muchlower sulfur content and a] higher lead response that would beobtainable by desulfurization ofsaidcracked fuel subsequenttothecracking operation. a

The fourth step of the present invention'contemplates the catalyticconversion'of the desulfurized cracking stock over catalysts capable ofsupportingcrackingor splitting reactions as an integral part oftheprocess.- The benefits of the '.-initial desulfurizlng step aretherebyreflected not only in a motor fuel of lower sulfur content whichneeds no further desiilfurizing treatment excentthe removal of but alsoinlonger active periods fertile cracking catalyst. v

fihe catalytic cracking step is carried out by heating-the crackingstock to a temperature in the range-orator, wrote-r. and passing the vvapors 'over an adsorbent mineral ore catalyst of the bauxite type saidcatalyst being hereinafter referred to as a bauxite catalyst,

straight run gasoline, it is preferred to separate naturally occurringgasoline almost completely from the desulfurized stock charged to thecrack ing unit. In this case, conversion temperatures are regulatedtoprevent over-conversion and coking, with a secondcatalytic or thermalcracking treatment beingperformed on unconverted cracking :stockifdesired after. separation of conversionproducts'fromthe initial crackingoperation. The adjustmentof'operating temperatures and contact time tosuit the feed stock thus is a matter of choice withinwthe scope, of thisinvention. .-z a H i The stream of vapors leaving the cracking catalystmay be cooled and passed to afractionator whereinthe gasoline vaporszandthe normally gaseous hydrocarbons are :taken of! overhead along withanyhydrogen sulfideresulting from ithe action of the crackingxcatalystwhile the unconverted constituents'ofithe cracking feed stock arewithdrawn asbottoms from the fractionator. 'lhis unconvertedmaterial maythen be passed over a secondcrackingcatalyst for further conversion tomotor fuel. The overhead 1 vapors 'from the first fractionator followingthe cracking unit may then be fractionated to sepastream from thecracking unit may be freed of rate normally gaseous hydrocarbons and toproduce an end-point high-octane cracked'motor fuel which requires nofurther treatment except possiblyclay treating; g,

Thelight gasesseparated-from .the eilluent hydrogen sulfide, compressed:and passed .to a

- vapor absorption unit for separation into a lightheat inthe' crackingoperation;

erfraction containing substantial amounts of hydrogen gas and a heavierfraction containing C: and C4 hydrocarbons; including substantialamounts of unsaturatedCa and C4 hydrocarbons. Said heavier fraction, orthe C: and C4 portionof it, lswellsuited to passage over a catalyst forproduction of catalyticpolymer gasoline which after fractionation may beblended with the cracked gasoline; The lighter fraction containinghydrogen and methane may, if desired, be returned to the streamofcracking stock, and used as a diluent gas .or source. of endothermalTo illustrate one embodiment of this invention, the following example isincluded. Such an'example,however, must not be construed as limiting theinvention since'other modifications within the scope of this inventionwill be apparent to those skilled in the art. I

' I Example I A'Texas Panhandle-crude oil was heated in a pipe still toa temperature of 800 F. and allowed .Presto flash in a separator whereinthe total vaporizable material was removedfrom the residual oil at anaverage vapor temperature of 750 P.

.The total vapor thus resulting was passed barrels of liquid oil perhour per ton of catalyst.

The treated vapors were then passed to a fractionating unit forseparation of hydrogen sulfide,

.normallygaseous hydrocarbons and straight run gasoline with about 360F. end point. The remaining desulfurized cracking stock was then chargedto a heater where the stream was vaporized and the vapors heated to atemperature of 950 F. The heated vapors were passed then to vaporizablematerial passes without any substantial cooling to a catalyst chamber Hfor desulfurization. Thetreated vapors then pass to fractionating unitI! wherein straight run gasoline and gaseous hydrocarbons along withhydrogen sulfide formed in l2 are taken overhead. The. overhead vaporsare cooled and fractionated in fractionator l4, from which theC; andlighter a chamber wherein an absorbent mineral ore cracking catalyst wasmaintained at substantially950 F. and about 30. poundspressure. Thevapors from the catalytic cracking unit were then cooled and passed to afractionator where the gasoline hydrocarbons and lighter gases weretaken off along with a small amount of hydrogen sulfide resulting from afurther decomposition of organic sulfur compounds by the crackingcatalyst.

The unconverted cracking stock remained as a residual oil which was thenpassed to a second catalytic converter for further cracking. The vaporstaken overhead from the primary fractionator were cooled and passed to asecond fractionator where gaseous hydrocarbons were separated from thegasoline. The gaseous hydrocarbons separated from the cracked gasolinewere passed to an absorption unit wherein hydrogen and lighter gaseswere separated from C3 and C4 hydrocarbons. Said C3 and C4 hydrocarbonscontaining a large percentage of unsaturates were then passed to acatalytic polymerization unit, and the efiluent from said unit afterfractionation produced an additional amount of gasoline of very highblending octane number.

The following comparative results illustrate the superior resultsobtained'bythis embodiment of the present invention as compared to theconventional refining of the same crude oil to produce successivelystraight run cracked and polymer gasoline. from the undesulfurized totalfraction vaporizable at 800 F.

Old New process process Total material vaporizable 800 F.:

Sulfur; percent.. 0. 25 0. 064 Reduction .do-. 78. 4

do-.. 88. 5 1.4 0.8 pereent 42.8

ur -do.- 0.12 0.045 Reduction .do. 62. 5 A. S. T. M. octane number 77. 578.0 TEL to 80 octane cc.. 0. 7 0. 3 Reduction in TEL ..percent. 67. 0Operating period of cracking catalyst 1 hours... 12 i8 Blend of straightrun, 'cracked and polymer gasoline:

S .peroent 0. 075 0. 024 Octane number. 72. 6 72. 0 TEL to 80 octane...cc. 1. 8 1. 0 Reduction in TEL peroent.- 44. 4

The figure illustrates schematically on'e embodiment of the processcomprising the present invention. According to this drawing, the crudepetroleum oil is fiash distilled in distillation unit In from which themixture of vapor and liquid pass to a separator ll. From the separatorthe hydrocarbons and hydrogen sulfide .are taken overhead and separatedfrom the end-point, low a sulfur straight run gasoline. The overhead gasmay then pass to a compressor l5 and a fractionator IS in which hydrogensulfide is removed by fractionation, along with part of the Ca hydror'carbons. The residual C3 and C4 hydrocarbons from thi operation areuseful in the manufacture of gasoline by thermal polymerization. Ifdesired, the C3 hydrocarbons may be largely retained by using chemicalmeans for the removal of hydrogen sulfide prior to the gas fractionationstep. The residual desulfurized liquid from I! then passes to a heater20 and thence to a catalyst chamber 2! for conversion of the heavyhydrocarbons to gasoline. The cracked vapors from 2| .pass toafractionator 22 where gasoline and gaseous hydrocarbons are removedalong with any decomposed impurities from unconverted cracking stock.The gasoline and gaseous hydrocarbons are fractionated in unit 28 toseparate C4 and lighter hydrocarbons from the cracked gasoline. Thegaseous hydrocarbons from 23 then may pass to a hydrogen sulfide removalunit 24, a compressor 25, and

. than to a vapor absorption unit 26, where Ca and Ct hydrocarbons areremoved, and sent to a catalytic polymerization unit 21 for conversionof unsaturates to polymer gasoline. The efiluent from 21 is thenseparated by fractionation in unit 28 to remove the unconverted Cs andC4 hydrocarbons which may then pass to thermal poly feed. The hydrogenand lighter hydrocarbons from 26 may be recycled if desired by alternatearrangement to the stream of cracking stock ahead of heater 20 to act asa diluent and source of endothermal heat to the cracking operation.

While the example and the drawing provide specific illustrations for theprocess of this invention, other modifications will become apparent inthe light of the foregoing disclosure, and limitations are applied onlyaccording to the appended claims.

I claim:

1. The process for producing motor fuel from crude petroleum oil whichcomprises fiash distilling said oil at a temperature between 600 and800? F., separating the total material vaporizable at said temperaturefrom residual oil, passins said total vaporizable material at vaportemperature without substantial cooling at pressures between atmosphericand pounds per square inch and fiow rates between 1 and 10 liquidvolumes of raw stock per hour per volume of catalyst, over a bauxitecatalyst whereby a substantial proportion of the organic sulfurimpurities is decomposed to hydrogen sulfide, fractionating thedesulfurized material to separate normally and 300 pounds per squareinch to partially con-' vert said heavy fractions by cracking intogasoline hydrocarbons, fractionating the vapors from the crackingcatalyst to remove normallyv gaseous hydrocarbons and hydrocarbon vaporscomprising a high octane cracked gasoline from unconverted heavyhydrocarbons, then separating the normally gaseous hydrocarbons bysubsequent fractionation from the gasoline hydrocarbons, separating the.gaseous hydrocarbons into a lighter and a heavier fraction, and passingsaid heavier gaseous fraction containing substantial amounts of olefinsover a catalyst for the production of polymer gasoline, fractionatingthe eilluent from the catalytic polymerization operation to obtainthereby additional high octane gasoline and combining said low sulfur,high leadresponse straight run gasoline with said highoctane cracked andpolymer gasoline to obtain superior yield of a valuable motor fuel.

2'. The processfor producing motor fuel from crude petroleum oil whichcomprises flash distilling said oil at a temperature between 600 and 800R, separating' the total material vaporlzable at said temperatures fromresidual oil, passing said total vaporizable'material withoutsubstantial cooling over a bauxite catalyst at pressures betweenatmospheric and 100 pounds per square inch, and flow rates between 1 andliquid volumes of feed stock per hour per volume of catalyst, whereby asubstantial proportion of the organic sulfur impurities is decomposed tohydrogen sulfide, fractionating the desulfurized material to separate astraight run gasoline, stabilizing said straight run gasoline to removenormally gaseous hydrocarbons and hydrogen sulfide and produce anend-point gasoline of low sulfur content and high lead response; heatingthe heavy fraction of said desuifurized material substantially denudedof gasoline and passing same over a'bauxite' catalyst at temperaturesbetween 800 and 1050 F. and pressures be-' tween atmospheric and 300pounds per square inch to partially convert said heavy fraction bycracking into gasoline hydrocarbons, fractionating the vapors from thecracking catalyst to re- ,move vapors comprising a high octane crackedgasoline from unconverted heavy. hydrocanbons,

condensing and'stabilizing said cracked gasoline and combining same withthe low-sulfur straight run gasoline to obtain a superior yield of a lowsulfur, high lead response motor fuel.

3. The process for producing motor fuel from crude petroleum oilwhichcomprises flash disa substantial proportion of the organic milfurimpurities are decomposed into'hydrogen sulfide, fractionating thedesulfurized material to segregate an end-point low sulfur straight rungaso-' line free,oi' hydrogen sulfide and a low sulfur cracking stock,heating said cracking stock and subjecting the vapors to crackingconditions to partially convert the heavy hydrocarbons into gasolinehydrocarbons, fractionting the vapors from the cracking operation toobtain a high octane low sulfur cracked gasoline and'b'lending saidcracked gasoline with said straight run gasoline to producea superiormotor fuel.

hydrogen sulfide, cooling and fractionating the desulfurized material toremove light gases and a straight [run gasoline with an end-point of 300F., heating the residual fraction of said desulfuriz ed material andpassing same over a bauxite catalyst at a temperature between 950 and1050 F., and pressures between atmospheric and pounds per square inch topartially convert said residual fraction into gasoline, cooling andfractionating the vapors from the cracking catalyst to remove vaporscomprising a high octane cracked gasoline and a light gas fraction highin hydrogen from unconverted heavy hydrocarbons, stabilizing saidcracked gasoline to remove said light gas fraction, passing said lightgas fraction to a vapor recovery system to separate Ca and C4hydrocarbons from the lighter gases containing principally methane andhydrogen, recycling a portion of the methane-hydrogen mixturewith thecracking stock ahead of the heater to supply endothermal heat to thecracking catalyst, and finally combining said high octane crackedgasoline with said low sulfur straight run gasolineto produce a superiormotor fuel i 5. The process for producing motor fuel, from crudepetroleum comprising passing the crude oil to a heating zone and thenceto a flashing zone to separate the vaporized and unvaporized material,the heat supplied to the heating zone being such that the temperature ofthe vaporized material is between 600 and 800 F., passing the vaporizedmaterial without cooling from the flashing zone into contact with asolid adsorbent bauxite catalyst at a pressure between atmospheric and100 pounds per square inch and a flow rate between one and ten liquidvolumes of feed stock per hour per volume of catalyst whereby asubstantial proportion of the organic sulfur impurities are decomposedinto hydrogen sulfide to yield a desulfurized stock, removing thehydrogen sulflde from the desulfurized stock, and passing desuliurifledstock in contact with a bauxite catalyst at a temperature between 800and 1050 F. and a pressure between atmospheric and 300 pounds per squareinch to partially convert the desulfurized stock into gasolineqontainlng a minimum of refractory cyclic sulfur compounds.

WALTER. A. SCHULZE.

